This invention relates to a semiconductor device applied in intelligent power modules (IPMs) used in inverter devices, and more specifically relates to the package structure, and the method of assembly of semiconductor devices.
FIG. 11 through FIGS. 13A, 13B show an assembled structure of the semiconductor device packages of the prior art. In FIG. 11, numeral 1 is a heat-dissipating metal base formed from copper; numeral 2 is an insulating circuit board with a conductor pattern formed on both faces of an insulating board; numeral 3 is a semiconductor chip (for example, an IGBT (Insulated Gate Bipolar Transistor)) mounted on the insulating circuit board 2; numeral 4 is solder joining layer, which joins the metal base 1 and insulating circuit board 2, and the insulating circuit board 2 and semiconductor chip 3; numeral 5 is an outer resin case; numeral 6 is an external terminal provided in a row in a wall portion of the outer resin case 5 (main terminals, control terminals); numeral 7 is a bonding wire (aluminum wire) connecting the L-shape leg portion 6a protruding from the external terminal 6 on the inside of the outer resin case 5 and the conductor pattern of the insulating circuit board 2; numeral 8 is a case lid; and numeral 9 is a sealing resin which fills the inside of the outer resin case 5, wherein the outer terminals 6 are formed integrally with the outer resin case 5 in insert molding of the wall portion thereof (see for example Japanese Unexamined Patent Publication No. 2003-249624, corresponding to U.S. Pat. No. 6,995,461). Separately from the wiring shown in FIG. 11, there are cases in which direct bonding wire 7 is used to connect the upper-face main electrodes of the semiconductor chip 3 and the external terminals 6.
A semiconductor device configured as above is assembled using the following procedure. First, the copper material is subjected to rolling, punching, and bending to fabricate the external terminals 6, which are set in prescribed positions within a mold used to form an outer resin case 5. Next, an injection resin such as PPS (polyphenylene sulfide), PBT (polybutylene terephthalate), or similar material is injected into the forming mold, and with the external terminals 6 integrated by insert molding, the outer resin case 5 is fabricated.
On the other hand, in the package assembly process, a board assembly in which the insulating circuit board 2 and semiconductor chip 3 are mounted on the metal base 1 is placed on the bottom face of the outer resin case 5, and the periphery of the metal base 1 is bonded to the outer resin case 5 with an adhesive (for example a silicone adhesive).
In the wiring process, subsequently, bonding wires 7 are connected between the L-shape leg portions 6a of the external terminals 6 drawn inside from the outer resin case 5 and the conducting pattern of the insulating circuit board 2. In this wiring process, an ultrasonic bonding method is used to connect the wires 7. After wiring of the wires 7, the resin case 5 is filled with a sealing resin 9, and the case lid 8 is fitted into place to complete the product.
After delivery of this semiconductor product to a customer, the product is for example mounted in an inverter device and the external terminals 6 are connected to a print board of the inverter device, for use in applications such as IPM (Intelligent Power Module) motor control.
In the above-described semiconductor device of the prior art, the package is configured with the external terminals 6. The external terminals 6 are insert-molded with the wall portion of the outer resin case 5 for each apparatus, positioned and arranged according to the current capacity of the semiconductor chip 3, position of placement, the details of the print board of the inverter device or other equipment, and other specifications. An example of such an arrangement of terminals appears in FIG. 12. FIGS. 13A and 13B are external diagrams of external terminals 6 used according to the magnitude of the current to be passed.
However, in the package assembly structure of FIG. 11 and FIG. 12, the placement positions and shapes of the external terminals 6 differ depending on the device model and on the specifications of custom products specified by a customer. For this reason, when a manufacturer manufactures a product, a forming mold for the outer resin case 5, designed according to the device model and to specifications specified for each custom product by a customer, must be newly fabricated and managed. Moreover, because it is in actuality difficult for an assembly robot to automatically set external terminals 6 with different shapes (see FIGS. 13A and 13B) in specified positions within the forming mold according to the product specifications, human labor is necessary to perform this task. As a result there is a long period from receipt of an order for a custom product to the delivery of the product, and moreover production costs are high.
This invention has been made in light of the above perspectives. An object of the invention is to resolve the above problems in providing a semiconductor device and a method of manufacture of a semiconductor device with an improved package assembly structure enabling manufacture of products in which the arrangement of external terminals mounted in the case can be made flexibly with different device models and various customer-specified specifications, with the outer resin case as a common component.
Further objects and advantages of the invention will be apparent from the following description of the invention.